We noted the following publication by Tsuda et al. critiquing work carried out by or in collaboration with the International Agency for Research on Cancer (IARC/WHO) [1], including the IARC technical publication No. 46 on “Thyroid health monitoring after nuclear accidents” (TM-NUC) [2], the project on nuclear emergency situations and improvement on medical and health surveillance (SHAMISEN) [3], and the IARC-led work on global thyroid cancer incidence patterns as per IARC core mandate [4, 5]. For the critique of our work Tsuda et al. used what they refer to as a “toolkit”, the purpose of which is to identify epidemiologic data misused by “powerful interests, particularly those with a financial stake…whose interest are not aligned with the public health sciences”. While Tsuda et al. may disagree with the conclusions reached in the publications, the selected items of the toolkit they apply to criticise it are misapplied – the work by IARC/WHO created no financial benefit for those publishing the work, and the mission of these organizations is explicitly oriented toward public health. We were also concerned to see that the authors confused study designs (page 15 [1]), bringing further misinterpretation of the weight of evidence to their critical evaluation of the papers that they are quoting.

IARC technical publication No. 46 “Thyroid health monitoring after nuclear accidents” is a forward-looking report coordinated by IARC that used scientific evidence and expertise of a large group of international scientists representing a wide spectrum of disciplines. The group was assembled to advise countries how to prepare immediate and long-term response in case of a nuclear power plant accident, with regard to a possible increase in thyroid cancer incidence related to such accident [2]. The report applied the principles of screening, and evidence from thyroid cancer pathology, natural history, epidemiology, diagnostics and clinical management in general population as well in the populations affected by the Chernobyl and Fukushima nuclear accidents [6, 7]. The report’s recommendations are not based on systematic reviews but drawn from all peer-reviewed publications relevant to the project objective. While we wish that our recommendations will never be needed, we believe they represent the recommended best practices for the data currently available.

IARC has been leading work on evaluation of global thyroid cancer incidence which provided convincing scientific evidence of an impact of thyroid care treatment patterns on incidence trends, first for adults [4], and then for children and adolescents [5] (latter not cited by Tsuda et al. [1]). Overdiagnosis in thyroid cancer is a well-recognized phenomena [8]. It globally affects a large number of people and has been acknowledged to result in overtreatment of many otherwise healthy individuals, exposing them to the potential for treatment-related complications and psychological harms, facts reflected in guidelines from the major professional organisations such as the American Thyroid Association (ATA) [9, 10]. The risk of overdiagnosis is also applicable in the setting of nuclear accidents and must be included in informed decision making when providing a system of optimal help for cases of radiation-induced thyroid cancer, to minimize harm to people by helping them avoid diagnostics and treatment they may not need.